European - US Voltage levels 1

[raisinbran]

Gentlemen,
Maybe this question has been raised before.
What are the reasons for the differences in voltage levels between the US and Europe - 4.16 kV (US) vs. 3.3 kV (Euro.) and 7.2kV (US) vs. 6.6 kV (Euro.)? Does it have anything to do with the 50 Hz. vs. 60 Hz. frequency differences?
Regards,
Raisinbran

 

[waross]

Different strokes for different folks.

Bill
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"Why not the best?"
Jimmy Carter

 

[jraef]

It has been discussed many times. The condensed version is: "just because".

There is really no rhyme nor reason to it, it is a result of legacy systems and the ability of suppliers to easily and inexpensively adapt to their neighbors as electrification expanded after WWI and grids started connecting to each other. Adaptation was irrelevant and unnecessary "across the pond" between Europe and America, and as Asia electrified, they imported more systems from Europe and so ended up adopting similar standards.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[prc]

It is seen that US voltages are slightly more than European Voltages(approx 10 %) to take care of regulation in transformers.In US nominal secondary voltage is got at loading and in Europe at no-load.

 

[ScottyUK]

Most of the UK voltages incorporated a 10% factor over a convenient nominal value, hence the large number of voltages divisible by 11. For example, 440V; 3300V, 6600V, 11kV, 33kV, 66kV, 132kV. I don't think there's any relationship to north american voltages other than coincidence.


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If we learn from our mistakes I'm getting a great education!

 

[fsck]

I suspect Darwin and "On the Origin of Species" might well apply. With two disjoint systems, and little if any interbreeding; they shall diverge, and have.

I'd attach little or no inference to where they have ended up; they got to their present state by meeting the differing needs of their respective environments.



BTW: if you want to see real divergence, look at CCITT vs Bell System standards some day...

 

[Skogsgurra]

First time I went to the US on a job, I noticed the 'buckets' along the streets and asked my local contact what voltage they were, 4160 volts - he answered.

I thought that was a really weird voltage level and asked how he could know it was just that voltage. 'They all are' he answered.

When I asked why one would chose such an odd voltage, he had no answer. He thought it was a perfectly normal and natural voltage. I still have no idea why the last 160 volts on top of the 4 kV were considered important. Covering a 4 % drop instead of the 10 % used in Europe? If so, it seems to be a more 'researched' percentage than the European 10 %.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[edison123]

60/50 Hz ratio thingy ?

Muthu

http://www.edison.co.in

 

[rbulsara]

Many odd looking voltages (in the USA) are related to the factor of square root of 3 and use of a bank of single phase transformers. 4160 is the result of nice 2400V line to N. 13.8kV ---->8000V L-N (a variation of 7.2 kV),
12.47kV -----> 7200V L-N, etc.


Multiple of 11 has always been a favorite trivia question in Europe and Asia, but there is no real technical reason. Although more common voltages 415V or 400V, 230V, 240V or 400kV are not multiple of 11.

Rafiq Bulsara

http://www.srengineersct.com

 

[Skogsgurra]

Thanks! This thread has become a lot more interesting than I thought possible!

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[prc]

Have look at Thread238-11181

 

[ScottyUK]

Rafiq,

415V is a utilisation voltage - the distribution voltage was 440V, which does have the '11' factor. The newer 400V standard is the result of European meddling harmonisation. I seem to remember that 400kV was the limit of proven technology at the time when the 400kV system was being built, and that is why it doesn't fit the pattern. Difficult to explain 275kV though!



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If we learn from our mistakes I'm getting a great education!

 

[waross]

In Canada there was a lot of distribution at 2400V delta. After WW2, the population increases and increasing industrialization demanded more capacity. Many utilities boosted the distribution voltage up to 4160, installed a neutral conductor and reconnected their distribution transformers line to neutral.
That is the origin of 4160V as a voltage as I know it. I was in school when our system changed over from 2400V to 4160V.
Some may note that 2400:4160V is exactly 20 times the now standard 120:20Volts. BUT, most of the 2400:4160V distribution was long gone before 120:240 became a standard. Go figure.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rbalex]

I've been digging through some old literature of mine, trying to find the original reference, but I just can't find it. As I understand it, originally ~150V was believed to be the lowest nominal lethal voltage. In the US, it was multiplied by 80% and 120V became the base standard so it would be "safe." All other US standard voltages are integral multiples of 120V or 120V x sqrt3. (Example: 4160V ~ 2400V x sqrt 3)

There are still a few remnants of 150V in the US National Electrical Code (NEC) with respect to grounding requirements.

Of course more people have been electrocuted (by definition they died) by 120V than any other voltage in the US. The lowest documented lethal voltage is now believed to be ~60V. Again multiply it by 80% and round off to 50V to become more or less the new “safe voltage” as reflected in many NEC and OSHA rules.

 

[waross]

In Canada and probably in the US, 110V was once the standard. This is the origin of references to One-ten, Two-twenty. Back in the 50's the standard in Canada was raised 1/2 volt per year. I understand that the target was 150 Volts but for a number of reasons the standard halted at 120 volts.
Appliances were rated for 110 Volts. Then for five years they were rated at 112 Volts. Five years later new appliances were rated at 115 Volts, the 117 Volts for five years.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[alehman]

The older parts of some (particularly eastern) cities in the U.S. have unusual voltages such as 4, 4.8, 11 and 22 kV. I had a project in central Detroit that was served with 4,800 delta. These are mostly ghosts of early electrification.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[raisinbran]

Guys,
Thank you all very much for the responses. Although no definite answer has been determined, the information that you provided was very interesting. I guess that variety truly is the spice of life.
Regards,
Raisinbran

 

[prc]

raisinbran, eventhough you concluded,let me supplement as this was a topic intriguing me.My search concluded as below:

Commercial Electric distribution was first done by Edison and his Manhattan DC lighting system was opened in September,1882.Edison took 100V as the voltage for his incandescent lamps.( Why 100 V?Round number,safe electrical voltgae to handle,but high enough to save copper in conductors)But it soon became clear that at the fag end of street the lamps were not burning well due to voltgae drop in line.Edison had to raise the generator voltage to 110 V ( there by distribution voltage became 110V!)to take care of the voltgae drop in line.To save copper, Edison raised the voltage to 220 V by adopting three wire Dc system .

When in 1886, first AC power distribution was installed at Great Barrington,Massachusets, Westinghouse and Stanley adopted 500 V as generator voltage 3 KV as transmission voltage and finally 100 V as distribution voltage.When first 3 phase Ac line was put up by Siemens to connect Lauffen with Frankfurt,generator voltage was 55V( half of 110V) and transmission was at 15Kv to be raised to 25 kV later.

According to clause 3.2.6 of Red book,(IEEE 141-1993),later distribution and transmission voltages were developed as multiples of 110
ie utilisation voltages of 110,220,440,550 V and distribution voltages of 2.2,4.4,6.6,13.2 Kv and transmission voltgaes of 22,33,44,66,110,220Kv

In US to keep the utilisation voltage same at full load, supply voltage was kept little more high ie 115 V.Then a new series occurred ie utilisation voltages of 115,230,460,575 V and distribution voltages of 2.3,4.6,6.9,13.8 and transmission voltages of 23,34.5,46,69,115,138,230 Kv etc,

As a result of continued problems with the operation of voltage sensitive lighting equipment and voltgae insensitive motors on the same system and the development of the 208Y/120V network system, supply voltages were raised again to multiples of 120 V
120,208Y/120,240,480,600V as utilisation voltages and 2.4,4.16,2.4,4.8,12,12.47Y/7.2 Kv as distribution voltages.